Your friend is wrong. It is strongly forbidden to do unlawful sexual activities.
A relationship between a man and a woman outside of marriage, which is what is called an unlawful relationship, is haraam, regardless of the level of this relationship and whether it goes as far as an intimate relationship or zina (sexual relationship), which is the most reprehensible and abhorrent type of sins and one of the gravest of major sins that poses the greatest danger to the individual’s religious commitment and faith, or it is less than that, such as looking, touching or kissing. All of that is haraam and these are types of zina in the general sense, and are things that lead to the greater immoral action.
Holy Qur'an says,
Say (O Muhammad SAW): "(But) the things that my Lord has indeed forbidden are Al-Fawahish (great evil sins, every kind of unlawful sexual intercourse, etc.) whether committed openly or secretly, sins (of all kinds), unrighteous oppression, joining partners (in worship) with Allah for which He has given no authority, and saying things about Allah of which you have no knowledge." [Holy Qur'an 7:33]
It is the Hadith S.A.W that,
"Once a young man came to the Prophet (S.A.W) asking permission for committing fornication. The people, then, started to rebuke him and said, "shush, shush." Then he (S.A.W) asked him, “Do you like it for your mother?” “No may Allah make me a sacrifice for you”, the man replied. “So are people.” the Prophet (S.A.W) asked again, “Do you like it for your daughter?” No may Allah make me a sacrifice for you,” the man replied. "So are people." The Prophet (S.A.W) commented. The Prophet asked once more, “Do you like it for your sister'?" the man replied “No may Allah make me a sacrifice for you.” The Prophet (S.A.W) commented. “So are people.” The Prophet (S.A.W) eventually asked, “Do you like it for your aunt?” The man replied" No may Allah make me a sacrifice for you.” The Prophet (S.A.W) commented, so are people." Whereupon the Prophet (S.A.W) placed his hand upon him and said, "O Allah! May you forgive his sins, purify his heart and make him chaste. The young man did not pay attention to any thing else thereafter.
[Reported by Al-Hakim]